Disclosed herein is a method to increase the field effect mobility of an electronic device by activating a donor-acceptor semiconductor in the device. The device may be, for example, an organic thin film transistor, or a photovoltaic device.
Thin film transistors (TFTs) are basic components of many electronic devices, including sensors, image scanners, and electronic display devices. Organic thin film transistors (OTFTs) offer advantages over conventional, silicon-based materials in that manufacturing costs can be reduced as well as providing mechanical properties such as the devices being physically compact, lightweight, and flexible. OTFTs are generally composed of a supporting substrate, three electrically conductive electrodes (gate, source and drain electrodes), a channel semiconductor layer, and an electrically insulating gate dielectric layer separating the gate electrode from the source and drain electrodes. The channel semiconductor is in turn in contact with the source and drain electrodes. The materials used to make the OTFTs, and the interfacial properties between various layers of semiconductor, dielectric, and electrodes can all affect the performance of the OTFTs.
As to the materials for development for printed OTFTs, the most challenging task is to obtain high performance semiconductors with a field effect mobility similar to or even surpassing conventional amorphous silicon semiconductors. To reach this goal, one approach is to continuously research for new semiconductor materials through molecular design. However, the development of new materials is often difficult and time consuming.
Therefore, an alternative approach to boost the performance of existing OTFTs through any novel physical or chemical means would be more attractive, since it eliminates the long development cycle of new materials.
Many semiconductors, for example those based on thiophene and/or fused-thiophene small molecules and polymers have been used for thin film transistors, and exhibited mediate mobility. Recently donor-acceptor semiconductors, such as polymers based on thiophene and/or fused-thiophene as donor and some electron deficient groups as acceptor, have shown a high field-effect mobility that is close to conventional amorphous silicon. Therefore, there is a need for physical or chemical methods that will further improve the field-effect mobility of OTFTs to equal to or surpass amorphous silicon semiconductor, especially OTFTs comprising a donor-acceptor type semiconductor composition.